Definition: You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
Input: Question: Two positive integers differ by 4, and sum of their reciprocals is 6. Then one of the numbers is

 Option A: a

 Option B: b

 Option C: c

 Option D: 4

 Option E: e

Option D